Method of making heat exchangers



Feb. 13,v 1968 T. F. PAULS l METHOD-OF MAKING HEAT EXCHANGERS .3Sheets-Sheet 2 Filed March 30, 1965 6 MZK INVENTOR. ITG 3 TH/SROA/FPAI/L5 Bkwa Mm."

A 7' TOR/VE V Feb. 13, 1968 T. F. PAULs METHOD OF MAKING HEAT EXCHANGERS3 Sheets-Sheet 5 Filed March ISO, 1965 @n m M INVENTOR. g THE/QONFPAULSBY gd@ ATTORNEY 3,363,261 METHD F MAKING HEAT EXCHANGERS Theron F.Pauls, Godfrey, Ill., assigner to @lin Mathieson Chemical Corporation, acorporation of Virginia Filed Mar. 30, 1965, Ser. No. 443,900 8 Claims.(Cl. 29-157.3)

ABSTRACT 0F THE DISCLSURE In the method of producing a heat exchangedevice from a panel having provided therein a plurality of iutegraltubes coextending with each other in substantially spaced relationship,said tubes being expanded out of corresponding opposite faces of saidpanel, the improvemeut comprising the step of forcing a major portion ofthe area of the panel on one side of each of said tubes out of the planeof said panel in a first direction while forcing a major portion of thearea of the panel on the other side of each of said tubes out of theplane of said panel in a second direction opposed to said firstdirection, thereby rotating each of said tubes out of the plane of saidpanel.

This invention relates in general to heat exchanger construction, andmore particularly to the fabrication of heat exchanger structures of themultiple parallel tube type.

A commonly used and eiicient type of heat exchange unit adapted to serveas an evaporator, air conditioner, condenser, internal combustion enginecooling radiator or the like is formed from a plurality of superimposedsheets of metal having internally disposed between the sheets a numberof conduits generally in a parallel spaced arrangement extending from afirst or intake header to a second or outlet header. One or more of suchunits may be employed, and the conduits or tubes serve to carry aninternal heat exchange medium such as Water or other coolant inconductive relationship with an external medium such as air or otherfluid passing between the tubes. This type of constru-ction is typ-icalof automobile radiators where, for example, the heated water issues fromthe heated block of the engine with the aid of a pump, first enters oneof the two headers, and then passes through a great number ofthin-walled, relatively dat, closely spaced tubes between which coolingair is blown and which extend usually vertically from one to the otherof the headers. Condensers are also frequently of the same type ofconstruction.

According to one heretofore known method of manufacturing illustrated inU.S. Patent 2,690,002, this type of heat exchange unit may be readilymanufactured to provide a great multiplicity of tubes in a sheet ofmetal. This method involves the application of a suitable predeterminedpattern of weld-inhibiting material between component sheets, pressurewelding all adjoining areas except those separated by theweld-inhibiting material thereby forming a unified composite panel, andinating along the unwelded areas to erect the tubes integral with theresultant tubed Lpanel. Full advantage heretofore has not been taken ofthis method, as the tubes formed are of rather flat or oval shape withthe cross-sectional major dimensions thereof lying within or parallel tothe panel in which the tubes are formed. In many applications it isdesirable that the cross-sectional major dimensions of the tubes beoriented at an angle to the plane of the panel; this design adapts theunits to fabrication as single pieces of large size, a number of whichmay then be put together for installations where the external mediumpasses through perforations in the panel transversely, rather thanpassing parallel to the panel along its surface.

In accordance with this invention it has been found nited States PatentO that the above-noted attributes may be obtained by treating a metalpanel formed in accordance with the abovementioned U.S. Patent2,690,002, in a unique manner. The panel may be formed with a multitudeof parallel tubes, the areas on the two sides of ea-ch tube forcedupwardly and downwardly to rotate the tube therebetween from itsoriginal position, simultaneously extending the metal between the tubes.The area between the tubes may then be perforated in a number of ways toallow for passage of a heat exchange medium through the sheet and acrossthe tubes. The area between the tubes may also be treated to providesecondary heat exchange areas to improve the heat transfercharacteristics of the device. This construction, while extremely simpleto fabricate and assemble, presents a practical and highly efficientheat exchanger adapted to provide a maximum amount of external heatexchange medium ow between the tubes with a minimum amount of turbulenceor impediment thereto.

Having thus generally described my invention, it becornes a principalobject thereof to provide a compact and highly efficient heat exchangedevice adapted for transfer of heat between an internal and externalheat exchange medium.

Another object of the present invention is to provide a heat exchangedevice having a plurality of parallel heat transfer tubes interconnectedbetween a pair of headers for maximum flow of an internal heat transfermedium.

Still another object of the present invention is to provide a heatexchange `device having a plurality of heat exchange tubesinterconnected between a pair of headers, the tubes being elongate incross-section with the crosssectional major dimension of the tube beingdisposed at substantially right angles to the normal plane of the panelfrom which the device is fabricated.

Still another object of the present invention is to provide a heatexchange device having a plurality of heat exchange tubes interconnectedbetween a pair of oppositely disposed headers, wherein the tubes arerotated 90 from the normal plane of the panel from which the device isfabricated to position the cross-sectional major dimension of the tubeat substantially right angles to the normal plane of said panel.

Yet another object of the present invention is to provide such a heatexchange device which is highly efficient, compact, and economical tomanufacture.

Still another object of the present invention is to provide a novelmethod of fabricating a heat exchange device having the aboveattributes.

Other objects and advantages will become apparent to those skilled inthe art as a detailed description of a particular embodiment proceedswith reference to the drawings which form a part hereof, and in which:

FIGURE 1 is a plan View of a blank employed in the instant invention;

FIGURE lA is a perspective view of a portion of the blank of FIGURE 1illustrating -a modification thereof;

FIGURE 2 is a cross-section taken along the lines II-II of FIGURE l toshow the internal construction of the blank;

FIGURES 3-6 are views similar to FIGURE 2 during subsequent steps of themanufacture;

FIGURES 7 and 8 are cross-sectional views similar to FIGURE 6illustrating two modifications;

FIGURE 9 is a partial plan view of a heat exchange device illustratingthe modifications of each of FIGURES 6-8.

Referring now to the drawings and particularly to FIG- URE l, there isseen an illustrative embodiment employing a blank indicated generally by10 produced as set forth in greater detail in the above-mentioned U.S.Patent 2,690,002. In accordance with that method, two

sheets 11 and`12 are superimposed with a pattern of weld-inhibitingmaterial indicated generally by 13 situated between the sheets 11 and12. As known in such method, the pattern 13 is a foreshortened versionof the desired pattern of tubes in the finished article. This patternconsists of a pair of parallel bands 14 and 15 which are spaced apartadjacent a pair of opposite edges of the stack of sheets formed ofindividual sheets 11 and 12. interconnecting the two bands 14 and 15 area plurality of bands 16 of weld-inhibiting material which cover theextent of sheets 11 and 12 intermediate bands 14 and 15 except forelongated parallel islands 17 which are free of weld-inhibitingmaterial, and which also extend between the bands 14 and 15. It will beapparent that the bands 14 and 15 correspond to the headers in thefinished article, and that the bands 16 correspond to the plurality ofinterconnecting tubes. In order to provide ingress and egress aperturesfor a heat transfer medium, the bands 14 and 15 are extended to an edgeof stacked sheets 11 and 12 as indicated .at 18 and 19. It will also beevident that a marginal portion of sheets 11 and 12 along opposite sidestransverse to the aforementioned opposite side has been left free ofweld-inhibiting material 13 and is surrounded by a peripheral marginalarea 20 with the exception of the strips 18 and 19 extending to one ofthe transverse edges.

For reasons to become evident, one or more of the islands 17 mayadditionally have provided a single band 21 of weld-inhibiting material,as seen in FIGURE l, or a plurality of bands 21, as seen in FIGURE 1A.The bands 21 or 21 are entirely isolated from the bands 14, 15, and 16.Also for reasons to become evident, each of the islands 17 may beperforated at each end thereof, as shown in FIGURE l at 22.

The stack of component sheets 11 and 12 with the weldinhibiting material13 sandwiched therebetween is then temporarily secured together as byclamps, spot welding or the like to prevent relative movement betweenthe sheets 11 and 12. The assembly thus formed is then heated to therequired temperature and set through a pair of pressure rolls whichexert sufficient pressure on the stack to firmly weld the sheets 11 and12 together into a single integrated panel in the areas not coated withthe weldinhibiting material 13. Simultaneously with the bondingoperation, the sheets 11 and 12 undergo a substantial reduction inthickness as well as an elongation in the direction of rolling wherebythe foreshortened pattern of weld-inhibiting material is stretched to alength corresponding to the desired pattern of tubes in the finishedarticle. FIGURE 2 illustrates in cross-section a portion of the blankafter such processing. The unified panel P results from the above-notedbonding of sheets 11 and 12 throughout their contacting surfaces notseparated by weld-inhibiting material, portions of which appear at 16 inFIGURE 2.

Referring again to FIGURE l, it will be evident that i all areas arebonded except those indicated by the pattern of weld-inhibiting material13. The islands 17, which ofcourse become bonded, may then be perforatedat each end thereof, as at 22, for reasons to become evident. Theperforations extend entirely through the panel P, and cover a majorportion of the width of each of the islands 17.

The pattern 13 may be subsequently infiated by introduction offluid-distending pressure. Thus, all areas covered by the pattern ofweld-inhibiting material 13 will -be distended to the desired shape inaccordance with the characteristics of the fiuid-distending pressure.For example, `as seen in FIGURE 3, parallel tubes 23 will be developedfrom the areas 16 of weld-inhibiting material shown in FIGURE 2. It willbe evident that all areas of the blank not having weld-inhibitingmaterial applied thereto will remain undistended.

The inflated panel P, as shown in part in FIGURE 3, may then be treatedin accordance with this invention to rotate the tubes 23 out of theplane of the panel P shown in FIGURE 3. Referring to FIGURE 4, thisrotation may be best accomplished by forcing the areas 24 betweenadjacent tubes 23 alternately up and down, thus rotating each of thetubes 23 between two such areas 24. For example, a series of parallelbars 25 acting on the upper face of the blank 12, between perforations22 may `be forced downwardly against alternate areas 24, in thedirection shown by the arrows 25. Simultaneously, a series of parallelvbars 26 also contacting the panel between perforations 22 may force theremaining alternate areas 24 upwardly, in the direction shown by thearrows 26. The motion of the areas 24 is materially facilitated by thepresence of perforations 22. Were it not for the perforations 22, theend portions of portion 24 would resist movement and impede the properrotation of the tubes 23 at such end portions. Accordingly, the portions24 illustrated in FIGURES 4 and 5 may be thought of as the portions ofislands 17 between the perforations 22, as seen in FIGURE l.

Considering again FIGURE 5, the action described above will force theareas 24 alternately up and down, necessarily rotating each of the tubes23 between adjacent areas 24 into a position rotated from its formerposition. As shown, the tubes 23 have been rotated approximately but itwill be evident that by appropriate control of the movement of bars 25and 26, the tubes 23 may be rotated any desired angle. As the tubes 23rotate, the areas 24 become reduced in thickness and extended in lengthdue to material ow occasioned by the action of the bars 25 and 26 inforcing the areas 24 from their previous positions. Thus, the effectiveheat exchange surface of the areas 24 is materially increased.

The areas Z4 may then be perforated in any number of fashions so as toprovide access of a heat exchange medium through the areas 24 andaccordingly across the tubes 23. As seen in FIGURE 6, for example, thismay be accomplished by merely punching a number of perforations 27 ofany desired shape in each of the areas 24. Thus, as seen in the planview of FIGURE 9, there will be provided a number of such perforations27 throughout the length of the island 17 allowing for plenary passageof a heat exchange medium.

Alternately, if it is desired to further increase the area of thematerial within the portion 24, a louver 28 may be struck out from thearea 24 and rotated at an angle to the plane of portion 24, for example90. Subsequently, this louver 28 may be extruded to thin out its surfaceand increase its length to provide a larger and thinner louver 28',further increasing the effective heat exchange surface of such louvers.FIGURE 9 illustrates the final position of the extruded louver 28 andthe area 29 of the portion 24 from which the louver was struck.

A still further method of forming perforations through the areas 24 isillustrated in FIGURE 8. This method requires that the island 17 shownin FIGURE 1 must have been previously provided with one or more-additional bands of weld-inhibiting material applied at the same timethat the pattern 16 was applied. One band may be applied between sheets11 and 12, as can be seen in FIG- URE l at 21. A plurality of bands maybe applied by providing additional sheets when forming the compositeblank. Thus, as can be seen in FIGURE 1A for example, a first band 21may be interposed between sheets 11 and 11', and a second band 21' maybe interposed between sheets 12 and 12. The pattern 16 may be theninterposed between sheets 11' and 12 and the composite blank treated inthe manner indicated above with reference to the blank of FIGURE 1.

In any event, the bands 21 or 21 are not inflated when the pattern 16 isinflated. Instead, these areas 21 or 21 remain undistended during therotation of the tubes 23, see FIGURE 8. Portions of the area 24 may thenbe struck out and rotated in much the same fashion as were the louvers28. However, when such an area is struck out and rotated, for example 90as shown at 30 in FIG- URE 8, it may be subsequently inflated byapplication of fluid-distending pressure to the areas 21 or 21 withinthe louver 30. Thus, as seen in FIGURE 9, the louver 30 which was struckout and rotated from the area shown as 31, may subsequently be providedwith one or more internal hollow tubes 32. Such construction materiallyincreases the area` of heat exchange surface available to the heatexchange medium passing through the areas 24.

It will be appreciated that the number of perforations shown herein aremerely exemplary and that any number of such perforations may beprovided. For example, a greater or lesser number of perforations 27 asshown in FIGURE 6 may be employed; additional louvers 28 as shown inFIGURE 7 may be provided in each of the portions 24; and one or more ofthe lovuers 30 as shown in FIGURE 8 may be provided in each of the areas24, with each of the louvers 30 having any number of desired internaltubes 32.

It will be evident that each of the resultant panels shown herein may beused alone or stacked up with a plurality of like panels to form a heatexchanger core structure of the multiple-tube type where the tubes ofone plate are staggered with respect to the tubes of an adjacent plateand where the tubes of each plate are juxtaposed opposite the fins of anadjacent plate. Similarly, as much heat exchange capacity as requiredmay be achieved by arranging the heat exchange units in multiples withthe headers of the several units being connected in parallel.

It will be evident from the foregoing description and accompanyingdrawings that there has been provided a heat exchange device and methodfor making the same which is believed to provide a solution to theforegoing problems and achieve the aforementioned objects. It is to beunderstood that the invention is not limited to the illustrationsdescribed and shown herein which are deemed to be merely illustrative ofthe best modes of securing out the invention and which are susceptibleof modification of form, size, arrangement of parts, .and detail ofoperation, but rather is intended to encompass all such modifications asare within the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:

1. In the method of producing a heat exchange device from a panel havingprovided therein a plurality of integral tubes coextending with eachother in substantially spaced relationship, and connected to at oppositeends thereof integral inlet and outlet headers, said tubes and headersbeing expanded out of corresponding opposite faces of said panel, theimprovement comprising providing slots between said tubes adjacent saidheaders and forcing a major portion of the area of the panel on one sideof each of said tubes out of the plane of said panel in a firstdirection while forcing a major portion of the area of the panel on theother side of each of said tubes out of the plane of said panel in asecond direction opposed to said first direction, thereby rotating eachof said tubes out of the plane of said panel, said headers beingsubstantially unchanged by the said forcing operation.

2. The method of claim 1 including the step of perforating each of theareas between said tubes at opposite ends thereof prior to forcing saidareas out of the plane of said panel.

3. The method of claim 2 further including the step of perforating theareas between said tubes forced ont of the plane of said panel.

4. A method of fabricating a heat exchange device from a composite panelformed of two superposed sheets having a pattern of Weld-inhibitingmaterial interposed between said sheets, said pattern including a pairof parallel spaced-apart bands located adjacent opposite edges of saidcomposite panel and extending to a transverse edge of said panel and aplurality of closely spaced-apart bands lying parallel to saidtransverse edge and joined at opposite ends with said pair of bands,said pair of bands and plurality of bands thereby defining islands freeof said weld-inhibiting material, said method comprising the steps of(A) expanding said pair of bands to form headers and plurality of bandsto form tubes within said composite sheet having their cross-sectionalmajor dimensions parallel to the plane of said composite sheet,

(B) providing at least two slots on said islands, one

slot adjacent each header,

(C) forcing alternate of said islands upwardly out of the plane of saidpanel and forcing a major portion of the remainder of said islandsdownwardly out of the plane of said panel, thereby rotating said tubesto position the cross-sectional major dimensions thereof at an angle tothe plane of said panel, said headers being substantially unchanged bythe said forcing operation.

5. The method of claim 4 further including the step of perforating saidislands in their position forced out of the plane of said panel.

6. The method of claim 5 wherein said step of perforating comprisesslitting a portion of each of said islands and rotating said portion outof the plane of said island.

7. The method of claim 6 further including the step of thinning andextending said portion.

8. The method of claim 5 further including the steps of (A) applying atleast one additional pattern of weldinhibiting material within each ofsaid islands upon formation of said composite sheet,

(B) slitting a portion of each of said islands in their position forcedout of the plane of said panel, and

(C) expanding the additional pattern of weld-inhibiting material withinsaid portion to form passageways within said portion.

References Cited UNITED STATES PATENTS 2,894,731 7/ 1959 Wurtz.

2,926,003 2/ 1960 Pulsifer.

2,999,308 9/1961 Rauls.

3,178,806 4/1965 Keith 165-171 JOHN F. CAMPBELL, Primary Examiner.

CHARLIE T. MOON, Examiner.

I. C. CLINE, Assistant Examiner.

